Reciprocating accumulation conveyor

ABSTRACT

A reciprocating accumulation conveyor comprised of at least one car and generally a plurality of cars secured together to form a conveyor train, which is reciprocated back and forth along the longitudinal axis thereof by a reciprocating drive assembly which is fastened to one of the cars. Each car carries at least one pusher mechanism thereon. The boxes to be transported by the conveyor ride on a track disposed above the car or train and are moved in a forward direction along the track by the pusher assemblies carried by the cars. Each pusher assembly has a pushing bar pivotally mounted thereon and a sensing arm. The pusher bars push the boxes or containers along the track in one direction and pivot under any box or container which they encounter on the rearward movement of the train until the bar clears the box, whereupon it returns to the upright position to push forward another container. The sensing arm extends forwardly of the pushing bar and container and acts to release the pushing bar upon contacting a forwardly disposed container thereby preventing a collision and possible arcing of the boxes or containers.

United States Patent [191 Taylor [1111 3,807,550 [451 Apr. 30, 1974RECIPROCATING ACCUMULATION CONVEYOR [75] Inventor: Edward W. Taylor,Pico Rivera,

Calif.

[73] Assignee: A. J. Bayer Company, Torrance,

Calif.

[22] Filed: Sept. 11, 1972 [21] Appl. No.: 287,600

Primary Examiner-Richard E. Aegerter Assistant Examiner-Hadd LaneAttorney, Agent, or FirmLyon & Lyon 7] ABSTRACT A reciprocatingaccumulation conveyor comprised of at least one car and generally aplurality of cars secured togetherto form a conveyor train, which isreciprocated back and forth along the longitudinal axis thereof by areciprocating drive assembly which is fastened to one of the cars. Eachcar carries at least one pusher mechanism thereon. The boxes to betransported by the conveyor ride on a track disposed above the car ortrain and are moved in a forward direction along the track by the pusherassemblies carried by the cars. Each pusher assembly has a pushing barpivotally mounted thereon and a sensing arm. The pusher bars push theboxes or containers along the track in one direction and pivot under anybox or container which they encounter on the rearward movement of thetrain until the bar clears the box, whereupon it returns to the uprightposition to push forward another containerL-The sensing arm extendsforwardly of the pushing bar and container and acts to release thepushing bar upon contacting a forwardly disposed container therebypreventing a collision and-possible arcing of the'boxes or containers.

10 Claims, 11 Drawing Figures 5@ g /7 l4 /5 2a 22 54 54 ,@0 Z 2% 54 7/ v5. /7 1 f4 f L55 o 20 o 42 m 4e (-5 Z Heg /e 55 m /7 /'4 RECIPROCATINGACCUMULATION CONVEYOR BACKGROUND OF THE INVENTION There are severaldifferent types of conveyors currently available for numerous differentapplications. One type of conveyor, and that with which this inventiondeals, is the accumulating conveyor. An accumulating conveyor transportscontainers, boxes or other items from one location to another, where, ifthe items thereon are not removed, will accumulate. A problemnecessarily arises when, throughone reason or another, items begin toaccumulate at the forward end of the conveyor. Continued accumulationwill cause the conveyor to back-up and often results in the items orcontainers being pressed together to the point of arcing above theconveyor. This presents a tremendous hazard both to the items and theworkers in the area, as the arc will soon break causing the itemscomprising the arc to be thrown from the conveyor, resulting in breakageand often personal injury.

One method of preventing arcing is-to deactivate the conveyor wheneverexcessive accumulation occurs. There are obvious disadvantages, however,in such an approach, as constant supervision is required as well as theloss of time during shutdown. A limited solution is found in U. S. Pat.No. 3,385,418, which teaches the use of a reciprocating conveyor toadvance a work piece from one station to another. However, that patentteaches a system which incorporates a precise stroke as a result offixed feeler plates and utilizes interconnected pushing assemblies whichrender the conveyor unsuited for hurried loading or long haul operationand necessitates total shut down to repair a single mechanism. Inaddition, that system comes to-a complete stop when the conveyor line isfull, thereby requiring various electrical controls, limit switches,their electrical circuitry and installation and maintenance costs. Inaddition to U. S. Pat. No. 3,385,418, the prior art shows otherconveying systems which circumvent the problem of arcing. However, noneof the systems taught thereby are suited for general operationconditions. They generally require exact loading and are not capable ofconveying articles over great distances.

SUMMARY OF THE INVENTION Briefly, the invention is comprised of a leastone and generally a plurality of conveyor cars secured together to forma conveyor train which is caused to undergo reciprocating movement by adrive assembly. Each car carries at least one pusher assembly whichoperates during the forward stroke of the conveyor train to push thecontainer or other item disposed thereover on a track above the cars inthe forward direction. During the rearward stroke, each assembly isdirected under the item therebehind, whereupon each item will again bemoved forwardly by the succeeding forward stroke of the conveyor train.Each pusher assembly has associated therewith a sensing arm whichrenders the pushing assembly inoperative during the forward stroke whenthe space between successive containers or items being conveyed reachesa set minimum distance.

It is the principal object of this invention to provide an accumulatingconveyor which continually advances containers or other items along atrack or supporting rails and automatically releases an item being movedtherealong at a predetermined distance behind any forwardly disposedstationary item to prevent contact.

It is another object of this invention to provide an accumulatingconveyor which is adaptable of operation over varying distances.

It is'still a further object of this invention to provide anaccumulating conveyor which prevents contact between adjacent items orcontainers being conveyed thereby despite imprecise loading.

It is yet another object of this invention to provide a accumulatingconveyor which prevents contact between adjacent items or containersbeing conveyed thereby which is of simple construction and economical tomanufacture and service.

IN THE DRAWINGS FIG. 1 is a plan view of a conveyor car having twopusher assemblies thereon.

FIG. 2 is a sectional side view of a conveyor car taken along line 22 ofFIG. 1.

FIG. 3 is a sectional view of the same conveyor car. The car havingmoved to the left with respect to the containers thereon.

FIG. 4 is a side elevation of the pusher assembly.

FIG. 5 is a side elevation of the drive conveyor car and drivemechanism.

' FIG. 6 is a sectional view of the conveyor car taken along line 6-6 inFIG. 5 and showing the container support track.

FIGS. 7 through 11 are a schematic representation of the movement of thecontainers on the conveyor system from left to right as the conveyorsystem undergoes reciprocating movement.

Referring now in detail to the drawings, the accumul'ating conveyorgenerally designated 10, is comprised of at least one and generally aplurality of conveyor cars 12 which are secured together at 14 in end toend relationship to form the conveyor or conveyor train. The number ofcars which is used in the train is determined by the distance which theconveyor is to span as well as other considerations such as the size ofthe items to be conveyed. Each car 12 has a pair of parallel side walls17 and end walls 18, each side wall having an outwardly extending flangemember 19 at the upper and lower ends thereof. Each car 12 carries atleast one pusher assembly, generally designated 16. The number of pusherassemblies per car is generally determined by the length of theindividual cars, fabrication considerations and again the size of theitems being conveyed. In the embodiment shown in the drawings, each car12 carries two pusher assemblies 16.

The pusher assembly is most clearly shown in FIG. 4 and contains apusher bar 20 which is rigidly secured to and'centrally disposed of on apusher support 22. The pusher support 22v is pivotally mounted at bothends thereof to the two side walls 17 of the conveyor car 12. Thepivotal mounting is accomplished in the illustrated embodiment by theuse of studs 24 which are rigidly secured to the side walls 17 andextend into support 22. Ball bearings 26 are carried by the support andare disposed about the studs 24 thereby providing low frictionalrotation of the support 22 and pusher bar 20 with respect to theconveyor car 12. A pair of rollers 28 are positioned on each end of thepusher bar 20. A weight 30 is rigidly affixed to the underside of thesupport roller 22 at a point forward of the lower portion of the pusherbar thereby tending to bias the pusher bar in a slightly forwardinclination with respect to the vertical axis, for reasons to bediscussed.

A releasing bar 32 is pivotally mounted'on the car forwardly of thepushing bar. The releasing bar is rigidly affixed by welding or the liketo a support 34 which ispivotally secured to side walls 17 in the sameor similar manner in which the pusher support 22 is secured. Thereleasing bar 32 has an upward bend at 35 therein about the underside ofsupport 34 and has a weight 36 secured to the forwardly extended endthereof which acts to pivot the locking bar clockwise about the support34. The underside of the rearward end of the releasing bar has a stop 38depending therefrom. As seen in the solid lines of FIG. 4, in a relaxedposition, the weight 36 on the releasing bar 32 causes the rearward halfthereof to be raised. lnthis position, the stop 38 and rearward most end40 of the releasing bar abut the lower rollers 28 on the pusher bar toprevent counterclockwise rotation thereof, while not impeding clockwiserotation. if the forward end of the locking bar were, however, raised,the pusher bar would befre to rotate unimpeded in either direction.

The pusher assembly 16 also has an elongated sensing arm42 which ispivotally mounted on the conveyor car 12 by means of a third support 44,studs 46 and ball bearings 48. A weight 50 is welded or otherwisesecurely affixed to the rearward portion of the sensing arm 42. A smallroller 52 is maintained on the rearward most end of the sensing arm anda pair of large sensing rollers 54 are mounted on the forward most endof. the sensing arm. It should be noted that the sensing arm, as thereleasing bar 32, has a slight upward bend at 55 therein beneath thesupport 44 whereby the forwardly extending end thereof and sensingroller 54 are in a slightly elevated position with respect to theconveyor car 12. it should be further'noted that in the preferredembodiment, rollers 52 and 54, as rollers 28 and the supports 22, 32 and44 have ball bearing mountings for reducing the friction created by themovement of the pusher mechanism thereby allowing for smoother operationand reduced part wear. It can be seen in FIG. 4, that when the sensingrollers 54 are depressed, the rearward end of the sensing arm 42 israised thereby raising the forward end of the releasing bar and loweringthe rearward end 40 thereof, whereby the lower rollers 28 on the pusherbar 20 are clear of the locking bar and stop 38, allowing the pusher barto rotate freely in either direction about studs 24. If the depressing;force on the sensing arm is removed, the weight 50 will cause therearward end of the sensing arm to drop, lowering the forward end of thereleasing bar, raising the rearward end thereof and thereby preventingany counterclockwise rotation of the pusher bar. The forward inclinationof the pusher bar 20 caused by the forward mounting of the weight 30 onsupport 22 reduces any tendency of the pusher bar and support to make acomplete clockwise revolution during operation and therefore assuressmoother operation of the conveyor. A depending flange 56 is provided onthe conveyor car 12 above the sensing arm 42 to limit the upwardmovement of the forward end of the sensing arm. A transverse flatretaining bar 57 straddles the bottom of the car 12 thereby preventingreleasing bar 32 from depressing below the car profile.

As noted above, at least one of these pushing assemblies 16 is carriedby each conveyor car,'with two being shown on each car in the drawings.Disposed above the conveyor cars, the end walls of which are securedtogether by means of bolts 58, is a track or rail 60, one embodimentthereof being shown in F l0. 6. The track shown therein is comprised oftwo sections, each having a car support portion 62, lower side wall 63,container support 64 and upper wall portion 66. The support and wallportions of the track define a lower trough 67 and an upper trough 69.The conveyor cars are adapted to move within the lower trough, while thecontainers 68 are positioned in the upper trough on the containersupport portion 64 of the track. The container support portion isdisplaced slightly above the pushing assemblies 16 except for the upperportion of the pushingbar 20, upper rollers 28 carried thereby andsensing rollers 54. To facilitate movement of the cars with-respect tothe track, which is stationary during the operation of the conveyor, alower supporting roller 68 and a pair of side guide rollers 70 areprovided on each car. The lower support roller 71 is positioned near oneend of the car while the side rollers are mounted near the opposite endthereof. When the cars are-secured together to form a train, the lowerrollers 71 support the cars, while the side rollers guide the carssmoothly along the lower trough 67formed by track 60. When the conveyortrain is complete, it should be apparent that one of the cars will carryan extra roller to properly support one of the end cars thereof. Extraside guide rollers may also be added to facilitate the movement of thetrain along the trough. it should also be-noted that while the track 60is shown horizontally disposed, it may be advantageous in someinstallations to tilt the track slightly with respect to the horizontalaxis to facilitate access to the containers or other items movingtherealong. Other embodiments of the track may also be utilized with theconveyor without affecting the operation.

ln use, the various cars 12 comprising the conveyor are bolted orotherwise secured together and the containers to be transported areplaced on the track thereover. The cars are then caused to undergoreciprocating movement on and with respect to the track by a driveassembly 72, generally shown in FIG. 5. The drive assembly comprises apower source (-not shown) which acts to rotate drive pulley 74 by meansof belt 76. A first crank 78 is'secured to the drive pulley by means ofa center shaft 80 and locking pin 82. The opposite end of crank 78 ispivotally attached to a second crank 84, through crankshaft 86. Thesecond crank 84 has a bifurcated end 88 in which rests drive pin 90. Thedrive pin is secured to the bifurcated end of the second crank through alocking pin (not shown) and rotatably mounted in support 92. Support 92is in turn affixed to a dual channelled quarter pulley 94 which rotatesabout shaft 96. one car in the conveyor train is the drive car 98 andhas a pair of apertured plates 100 disposed at each end thereof and heldbetween the adjacent cars by securing bolts 58, as shown in FIG. 5. Afirst drive wire 102 is secured to one of the plates 100 through afitting 104 and is directed therefrom through a channel in the quarterpulley 94 and fastened to a turnbuckle 106 located beneath the pulleychannel. Another drive wire 107 is similarly attached to the other plate100 and directed therefrom through the other channel in the dualchannelled quarter pulley to a second turnbuckle 109. The twoturribuckles are then joined through a bent fitting 112 and areadjustable to maintain the drive wires in a taut disposition during theThe operation of the pusher assemblies on thecontainers is easilyunderstood with reference to the drawings. When the containers areplaced on the track and the conveyor train is moving to the right asshown in FIG. 2, the sensing rollers 54 are in the raised position dueto the weight 50 which is secured to the sensing arm causing that arm topivot in a counterclockwise direction, which, as noted above, lowers therearward end of the sensing arm causing the forward end of the releasingbar to lower under the pressure of weight 36 secured thereto and therearward end thereof to correspondingly raise, thereby preventing anycounterclockwise movement of the pushing bar. Therefore when theconveyor cars move to the right the pushing bars 22 will come intoabutment with the containers and con tinued travel of the cars in theforward direction (to the right) will cause the containers to be carriedalong the track 60 by the force of the pusher bars pushing against thecontainers, as the pusher bars are restrained against counterclockwisemovement by the upraised position of the rearward end of the releasingbar. The forward movement of the containers will continue until eitherthe end of the clockwise stroke of the one-quarter pulley, whereupon thecars will begin to move rearwardor to the left as shown in FIG. 3, oruntil the sensing rollers 54 abut a forwardly disposed container whichwas not removed from the forward end of the conveyor. In such asituation, the sensing roller would be depressed by the weight ofthecontainer, which, through the pivoting action of the sensing arm aboutroller 44, raises the forward end of the releasing bar 32 and lowers therearward end thereof, thereby freeing the lower end of the pusher barand allowing the pusher bar to undergo counterclockwise rotation. Thepusher bar would then simply release the container, pivoting thereunderin a counterclockwise direction as the bar passed thereunder. The use ofrollers 28 on the pusher bar reduce the friction as the bar passes underthe container disposed thereover.

FIGS. 7-11 are illustrative of the above described procedure. In FIG. 7the conveyor train has just finished its forward stroke (to the right)and begins its rearward movement. As the pusher assemblies pass to therear, the pusher bars strike the forward edge of the rearwardly disposedcontainers and are caused to pivot in a clockwise direction as they passthereunder. There is never any obstruction in the assembly to clockwiserotation of the pivot bars. FIG. 8 represents the end of the rearwardstroke, whereupon the cars again move in the forward direction. Thepusher bars then abut the rearward edge of the containers and due to thedisposition of the releasing bar 32 caused by the upraised sensingrollers 54, the pusher bars are prevented from undergoingcounterclockwise rotation and hence begin to push the containersthereabove in the forward direction. If a container had been removedfrom the conveyor, the container next in line would be pushed forward tothe location previously occupied by the removed container. If, however,a forwardly disposed container is not removed, as shown in FIGS. 7-11,contact between containers is avoided by the releasing action of thepusher assemblies. When the forwardly extending sensing roller contactsa forwardly disposed container, the forward end of the sensing arm isthen depressed, releasing the pushing bar and the container therebypreventing contact. This position is represented by FIG. 9. As theforward movement continues,

the third container is moved forward until the sensing 4 roller of thepushing mechanism thereunder is depressed by the forwardly disposedcontainer, whereupon the third container is released as seen in FIG. 10.If none of the containers were removed from the conveyor and no newcontainer added at the rearward end thereof the conveyor would appear asseen in FIG. 11. If a container were then removed, those containersrearwardly disposed to the removed container would be advanced onelocation by operation of the pushing mechanisms. It can be seen that theminimum distance which can be caused to occur between adjacentcontainers is the difference of the distance between the pusher bar andsensing roller of one pusher mechanism and the length of the containerwhich is being moved thereby. Therefore by adjusting the length of thesensing arms 42, this distance can be varied to suit'particularoperations.

Various changes and modifications may be made in 'carryingout thepresent invention without departing from the scope and spirit thereof.Insofar as these changes and modifications are within the purview of theappended claims, they are to be considered as part of the invention. 7

I claim:

1. An accumulation conveyor for use in combination with a reciprocatingdrive means for forwardly transporting items along a track comprising atleast one conveyor car disposed below said track, said conveyor carhaving elongated side portions and parallel end walls, at least onepusher assembly carried by said conveyor car, said pusher assembly beingcomprised of a first support extending between said elongated sideportions and pivotally mounted therebetween, a pusher bar rigidlyaffixed to said support, means carried by said pivotally mounted supportfor biasing said pusher bar in a substantially vertical position, asecond support extending between and pivotally secured to said sideportions of said conveyor car forwardly of said first support, anelongated arm rigidly affixed to said second pivotally mounted support,said arm having a raised forward portion, means for biasing the raisedforward portion of said arm above the upper surface of said conveyorcar,

a third support extending between and pivotally secured to said sideportions of said conveyor carbetween said first and second supports, areleasing bar rigidly affixed to said third pivotally mounted supportand extending between said pusher bar and said elongated arm, theforward end of said releasing bar extending over the rearward end ofsaid elongated arm, means for biasing said releasing bar downwardly uponthe portion of said arm disposed thereunder so that the rearward end ofsaid releasing bar prevents forward rotation of said pusher bar whensaid end is an elevated position and releases said pusher bar whendisposed in a lowered position, and attachment means carried by wardinclination with respect to a vertical axis passing therethrough.

3. The combination of claim 2 including means for reducing the frictionbetween said releasing bar, said pushing bar and said elongated armduring movement thereof. v

4. The combination of claim 3 including means for limiting the upwardmovement of the forward portion of said elongated arm.

5. The combination of claim 4 wherein said friction reducing meanscomprises rollers mounted on each end of said pusher bar and therearward end of said elongated arm.

6. The combination of claim 5 including a roller mounted on the raisedforward end of said elongated arm to facilitate movement of said raisedend under a stationary item positioned on Said track.

7. An accumulation conveyor for use in combination with a reciprocatingdrive means for forwardly trans- I porting items along a trackcomprising at least one conveyor car disposed below said track, saidconveyor car having elongated side portions and parallel end walls, atleast one pusher assembly carried by said conveyor car, said pusherassembly being comprised of a pusher bar pivotally mounted on theconveyor car, means for biasing said pusher bar in a substantiallyvertical position, an elongated arm having a raised forward portion andbeing pivotally mounted on said car forwardly. of said pusher bar, meansfor biasing the raised portion of said arm above the surface of saidconveyor car, a releasing bar mounted on said car and extending betweensaid pusher bar and said elongated arm, said releasing bar abutting saidpusher-bar and preventing forward rotation the'reof when the forwardportion of said elongated arm is above the surface of said conveyor carand pivoting out of engagement with said pusher when the forward portionof said elongated arm is in a lowered position thereby releasing saidpusher bar, and attachment means carried by said conveyor train andadapted to be secured to said drive means for imparting reciprocatingmovement to said conveyor train.

8. An accumulation conveyor for use in combination with a reciprocatingdrive means for forwardly transporting items along a track comprising atleast one conveyor car disposed below said track, said conveyor carhaving elongated side portion and parallel end walls, at least onepusher assembly carried by said conveyor car, said pusher assembly beingcomprised of a pusher bar pivotally mounted on the conveyor car, meansfor bias ing said pusher bar in a substantially vertical position, anelongated arm having a raised forward portion and being pivotallymounted on said car forwardly of said pusher bar, means for biasing theraised forward portion of said arm above the surface of said conveyorcar, a releasing bar mounted on said car and extending between saidpusher bar and said elongated arm, the forward end of said releasing barextending over the rearward end of said elongated arm, means for biasingsaid releasing bar downwardly upon the portion of said arm disposedthereunder sothat the rearward end of said releasing bar preventsforward rotation of said pusher bar when said end is in an elevatedposition and releases said pusher bar when disposed in a loweredposition, and attachment means carried by said conveyor train andadapted to be secured to said drive means for imparting reciprocatingmovement to said conveyor.

tram.

9. The combination of claim 8 wherein said pusher bar biasing meansmaintains said pusher bar in a forward inclination with respect to avertical axis passing therethrough.

10. The combination of claim 9 including means for reducing the frictionbetween said releasing bar, said pushing bar and said elongated armduring movement

1. An accumulation conveyor for use in combination with a reciprocatingdrive means for forwardly transporting items along a track comprising atleast one conveyor car disposed below said track, said conveyor carhaving elongated side portions and parallel end walls, at least onepusher assembly carried by said conveyor car, said pusher assembly beingcomprised of a first support extending between said elongated sideportions and pivotally mounted therebetween, a pusher bar rigidlyaffixed to said support, means carried by said pivotally mounted supportfor biasing said pusher bar in a substantially vertical position, asecond support extending between and pivotally secured to said sideportions of said conveyor car forwardly of said first support, anelongated arm rigidly affixed to said second pivotally mounted support,said arm having a raised forward portion, means for biasing the raisedforward portion of said arm above the upper surface of said conveyorcar, a third support extending between and pivotally secured to saidside portions of said conveyor car between said first and secondsupports, a releasing bar rigidly affixed to said third pivotallymounted support and extending between said pusher bar and said elongatedarm, the forward end of said releasing bar extending over the rearwardend of said elongated arm, means for biasing said releasing bardownwardly upon the portion of said arm disposed thereunder so that therearward end of said releasing bar prevents forward rotation of saidpusher bar when said end is an elevated position and releases saidpusher bar when disposed in a lowered position, and attachment meanscarried by said conveyor car and adapted to be secured to said drivemeans for imparting reciprocating movement to said conveyor train. 2.The combination of claim 1 wherein said pusher bar biasing meansmaintains said pusher bar in a forward inclination with respect to avertical axis passing therethrough.
 3. The combination of claim 2including means for reducing the friction between said releasing bar,said pushing bar and said elongated arm during movement thereof.
 4. Thecombination of claim 3 including means for limiting the upward movementof the forward portion of said elongated arm.
 5. The combination ofclaim 4 wherein said friction reducing means comprises rollers mountedon each end of said pusher bar and the rearward end of said elongatedarm.
 6. The combination of claim 5 including a roller mounted on theraised forward end of said elongated arm to facilitate movement of saidraised end under a stationary item positioned on said track.
 7. Anaccumulation conveyor for use in combination with a reciprocating drivemeans for forwardly transporting items along a track comprising at leastone conveyor car disposed below said track, said conveyor car havingelongated side portions and parallel end walls, at least one pusherassembly carried by said conveyor car, said pusher assembly beingcomprised of a pusher bar pivotally mounted on the conveyor car, meansfor biasing said pusher bar in a substantially vertical position, anelongated arm having a raised forward portion and being pivotallymounted on said car forwardly of said pusher bar, means for biasing theraised portion of said arm above the surface of said conveyor car, areleasing bar mounted on said car and extendinG between said pusher barand said elongated arm, said releasing bar abutting said pusher bar andpreventing forward rotation thereof when the forward portion of saidelongated arm is above the surface of said conveyor car and pivoting outof engagement with said pusher when the forward portion of saidelongated arm is in a lowered position thereby releasing said pusherbar, and attachment means carried by said conveyor train and adapted tobe secured to said drive means for imparting reciprocating movement tosaid conveyor train.
 8. An accumulation conveyor for use in combinationwith a reciprocating drive means for forwardly transporting items alonga track comprising at least one conveyor car disposed below said track,said conveyor car having elongated side portion and parallel end walls,at least one pusher assembly carried by said conveyor car, said pusherassembly being comprised of a pusher bar pivotally mounted on theconveyor car, means for biasing said pusher bar in a substantiallyvertical position, an elongated arm having a raised forward portion andbeing pivotally mounted on said car forwardly of said pusher bar, meansfor biasing the raised forward portion of said arm above the surface ofsaid conveyor car, a releasing bar mounted on said car and extendingbetween said pusher bar and said elongated arm, the forward end of saidreleasing bar extending over the rearward end of said elongated arm,means for biasing said releasing bar downwardly upon the portion of saidarm disposed thereunder so that the rearward end of said releasing barprevents forward rotation of said pusher bar when said end is in anelevated position and releases said pusher bar when disposed in alowered position, and attachment means carried by said conveyor trainand adapted to be secured to said drive means for impartingreciprocating movement to said conveyor train.
 9. The combination ofclaim 8 wherein said pusher bar biasing means maintains said pusher barin a forward inclination with respect to a vertical axis passingtherethrough.
 10. The combination of claim 9 including means forreducing the friction between said releasing bar, said pushing bar andsaid elongated arm during movement thereof.